When the LTE system works on the same frequency band,

interference occurs between the UEs on the edge of cell becausethey are close to each other and use the same resources. In thiscase, the performance of the UEs deteriorates. The inter-cellinterference coordination (ICIC) technology can be used to changeinterference distribution to improve the throughput on the edge ofcell.When static DL ICIC is used, the entirebandwidth is divided into three parts, each ofwhich serves as the edge band of a cell forreuse. In this case, network planningengineers need to perform frequencyplanning.Page 5

Different from WCDMA cell ID, LTE cell ID consists of 20-bit eNB ID and8-bit cell ID, which ensures that the LTE cell ID is unique in the entirenetwork. If the PLMN (MCC + MNC) is used, the LTE cell ID is uniqueworldwide. The WCDMA cell ID is unique on each RNC, the GSM andCDMA cell ID also is similar to the WCDMA cell ID.The eNB involves the local cell ID, sector ID, and cell ID. It is advised toplan the three IDs starting from 0, which ensures that they are consistent.

Considerations for Actual Planning

Page 8

Operator may provide numbering rules for different areas and cities. Ifthe operator have no additional requirements, the only principle of eNBID planning is to confirm it s unique in the whole network.

In LTE system, TAC is similar to the location area and routing area ( LAC ) in 2G/3Gnetworks, the tracking area (TA) is used for paging and route update. TA planningaims to reduce location update signaling caused by location changes in LTE system.

TAI list

TA list identify the tracking areas that the UE can enter without performing a trackingarea updating procedure. The TAIs in a TAI list assigned by an MME to a UE pertain tothe same MME area. Additionally, the TAIs in a TAI list assigned by an MME to a CSfallback capable UE pertain to the same location area. In this case, the defining of therelationship between the tracking area(s) and the location area(s) is operator specific.

In LTE system, if an UE changes the TAs in the TAI list, TA update wont be triggered.

Page 10

TA Planning Principle

A TA should be medium. The limitations by the EPC must be considered. (Currently,

each TA supports a maximum of 30 eNBs in the EPC. USN9810V900R001C03SPC300 100 eNB )

When the suburban area and urban area are covered discontinuously, anindependent TA is used for the suburban area.

TA should be planned for a continuous geographical area to avoid TA discrete

distribution.

The paging area cannot be located in different MMEs.

The mountain or river in the planned area can be used as TA boundary to reduce theoverlapping depth of two TAs. In this way, fewer location updates are performed onthe edge of TA.

The LAC planning in the existing 2G/3G networks can serve as a reference forplanning TAC.

PCI PlanningIn LTE system, the physical cell identifier (PCI) is used to differentiate radio signals of differentcells. PCI can be reused in the whole network, but should be unique in one coverage area toensure UE can distinguish different cells.PCI= 3 * PCI Group ID+ ID within PCI GroupUE captures ID within PCI Group through demodulating PSCH, and captures PCI Group IDthrough demodulating SSCH.The function of PCIs in the LTE system is similar to that of scrambling codes in WCDMAsystem. PCI planning also aims to ensure the reuse distance.Differences between a scrambling code and a PCI: The scrambling code ranges from 0 to 511whereas the PCI ranges from 0 to 503. In addition, the protocols do not have specificrequirements for scrambling code planning. Therefore, only the reuse distance needs to beensured in scrambling code planning. For PCI planning, however, 3GPP protocols require thatthe value of PCI/3 should be 0, 1, or 2 in each eNB.UENT 3.6 can be used for PCI planning.Page 13

Actual ConsiderationsPCIs should be reserved for indoor coverage.For multiple cities, PCIs should be reserved for border coverage.For a high site that may lead to cross-cell coverage, a large reusedistance needs to be set independently.

Neighbor Cell Planning

The method of LTE neighbor cell planning is similar to neighbor planning of

GSM/WCDMA/CDMA. Currently, the planning method and tool (UNET 3.6) for LTE areavailable.The configuration is different from GSM/WCDMA/CDMA . There is no BSC/RNC in the LTEsystem. When an eNB cell is configured as neighbor cells of other eNBs, external cells mustbe added first, which is similar to the scenario where inter-BSC/RNC neighbor cells areconfigured on the BSC. That is, neighbor cells can be configured only after the correspondingcell information is added.

ADD EUTRANINTRAFREQNCELL; DSP EUTRANEXTENALCELL

Page 16

ANR and Neighbor Cell Planning

Automatic Neighbor Relation (ANR) can automatically add and maintain

neighbor relations. However, ANR function is based on UEs measurements ,so it is closely related to the traffic load in the entire network and additionaltime delay is introduced to the handover process.Therefore, ANR is not recommended in initial phase of network construction.After initial neighbor relations configured and the number of UEs increasing,ANR can be used to detect missing neighbor cells and add neighborrelations, to improve handover and other performance.

PRACH Planning - Logical Root Sequence

Indexes

What is the logical root sequence index?

The random access preambles are generated from ZadoffChu sequences that with zero correlation zone. There are 64 available preamble sequences in each cell.The 64 preamble sequences are first generated from aroot Zadoff-Chu sequence using cyclic shift. If less than 64preamble sequences are generated, the remaining aregenerated from the next root Zadoff-Chu sequencecorresponding to the logical index. The logical root sequence index is sentto the UE through the SIB2.

Page 21

PRACH Planning - Logical Root Sequence

Indexes

Zadoff-Chu sequence A Zadoff-Chu sequence has good self-correlation and crosscorrelation and is defined as follows:

xu n eN ZC

un ( n 1)N ZC

, 0 n N ZC 1

indicates the length of the Zadoff-Chu sequence, and u indicates

the physical root sequence index. The relation between the logicalroot sequence index and physical root sequenceindex is defined inu thprotocols. The preamble sequences are generated from the

N ZC N CS 1, N CS 0 for unrestricted sets

for unrestricted sets

Causes for Planning the Root Sequence Index

is selected randomly or assigned by the eNB. To reduce interference of

preamble sequences between neighbor cells, the root Zadoff-Chusequence index need to be planned properly. The planning aims to assign the root Zadoff-Chu sequence index for cells

to ensure that different preamble sequences are generated for neighbor

cells through the index. In this way, interference of preamble sequencesbetween neighbor cells can be reduced.

Page 23

Factors Affecting the Access Radius

Preamble format

Preamble Format

Ncs

Maximum Cell Radius

0

14.5 km

77.3 km

29.5 km

100 km

N CS 1.04875 (6.67 r TMD 2)

The unit of r is km. The unit of TMD is sec. The value of

cell radius and maximum time delay extension.

Page 24

N CS is subject to the

How to Plan (Take Low Speed Cell as an Example)

Step 1: The Ncs value is determined by the cell radius. If the cell radius is10 km, the Ncs value is 77.

Step 2: The value of 839/77 is rounded down to 10, that is, each indexcan generate 10 preamble sequences. In this case, 7 root sequenceindexes are required to generate 64 preamble sequences.

Step 3: The number of available root sequence indexes is 119 (0, 7, 14

833).

Step 4: The available root sequence indexes are assigned to cells. Theassignment principles are similar to those for PCIs.The planning method of high speed cell is similar to that of a lowspeed cell. The algorithm for determining available root sequenceindexes, however, is more complex.Its recommended to use UNET 3.6 for PRACH planning.